Personal computing and electronic devices, such as laptop computers, media players, cellular telephones, smartphones, personal digital assistants (PDAs) and the like are becoming ubiquitous. Such computing devices typically employ a display to output graphics, text, and other visual information. Often the display is covered by a panel that protects the display from damage and contamination. In many devices the panel is formed from glass. Glass panels may be preferable in that they may substantially avoid interfering with a user's view of the display due to desirable optical properties thereof.
The ability to provide such devices in decreasing sizes at affordable costs to consumers while still maintaining or increasing the power, operating speed and aesthetic appeal of such devices, has contributed greatly to this trend. Unfortunately, the trend of smaller, lighter and more powerful portable electronic devices presents continuing design challenges in the actual production of these devices, particularly where such devices have relatively large displays. Some design challenges associated with such portable electronic devices include the ability to provide clear and robust visual displays, minimize power consumption, and dissipate heat without sacrificing size, processing power or user convenience.
For example, many users like to be able to use their portable electronic devices at virtually any time, such as while the user is on the go or simply outdoors. As many consumers know, however, the use of a portable electronic device is not always ideal when the device is exposed to direct sunlight or when the ambient environment is unduly bright. For example, the relatively small size of a portable device having a powerful processing system can by itself lead to a significant amount of heat generation. As many consumers can attest, such a heated device condition can then be exacerbated by exposure to direct sunlight or being outdoors. The rapid heating or overheating of a portable electronic device in use in direct sunlight can be even further accelerated where the device has a large display screen that permits the ready passage of solar energy into the device.
An anti-reflective coating (or ARC) can be applied to the portable electronic device that can prevent overheating. Generally, the ARC is applied at a front surface of a cover glass, or glass panel. The ARC can be formed of many individual transmissive layers having differing optical characteristics that when taken together can provide an effective shield from the heating effects of direct sunlight. The ARC may additionally or alternatively improve the usability of the display by reducing reflections associated with viewing the display through the glass panel. The ARC and/or various other functional layers may be applied to the glass panel as a film. However, such films may be relatively weaker than the glass panel and may propagate cracks into the glass under certain circumstances.
Accordingly, strengthened films for display panels or other substrates may be desirable.